Non‐Newtonian fermentation broths: Rheology and mass transfer

A large number of submerged citric acid fermentations in a beet molasses substrate was studied.The development of Aspergillus niger from conidia to pellets was followed. Rheological characteristics of the fermentation broth including the pellets were determined. The results obtained confirm the fact that the non-Newtonian pseudoplastic behaviour of the fermentation broth was due to the presence of mycelial pellets. The most significant changes in rheological properties occurred during the period of maximal citric acid production and increase in biomass.

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“…The shear stress (r) of the fermentation broth was characterized by the power law model of Ostwald-de Waele (Blanch and Bhavaraju 1976).…”

Section: Methodsmentioning

confidence: 99%

Submerged citric acid fermentation: rheological properties ofAspergillus niger broth in a stirred tank reactor

Berovič¹,

Cimerman²,

Steiner

et al. 1991

Appl Microbiol Biotechnol

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“…Both of these effects have a profound in¯uence on the rheological properties of the fermentation broth. Several factors, viz., mycelial concentrations, the morphology of the organism, and the production of extracellular material by the organism [50], which in¯u-ence the broth rheology change during the time course of batch fermentation.…”

Section: Fragmentation Of Hyphal Elementsmentioning

confidence: 99%

“…Blanch and Bhavaraj [50] have ®rst considered the decrease in diameter of the pellets by chipping pellicles from the surface. This type of damage is correlated by the Eq.…”

Section: Fragmentation Of Hyphal Elementsmentioning

confidence: 99%

Understanding the morphology of fungi

Pazouki

Panda

2000

Bioprocess Engineering

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Filamentous fungi comprise an industrially very important collection of microorganisms, since they are used for the production of a wide variety of products ranging from primary metabolites to secondary metabolites and further on to industrial enzymes (such as proteases, lipases and antibiotics). It is known that fungal morphology is often considered as one of the key parameters in industrial production. For the production of fungal metabolite products, the desired morphology varies from one product to another. Many parameters affect the morphology of fungi during the process of fermentation, among them speed of agitation, speci®c growth rate, dissolved oxygen, number of spores or conidia per liter of fermentation broth are important and should be considered when higher yield is desired in the process. It is, therefore, of considerable importance to understand the mechanism underlying the morphology of the cell, its growth and product formation by ®lamentous fungi. Such knowledge may be used in the optimization of the microbial process. Several literatures with various fungi to study their morphology, relating enzyme or product production to the character of the fungi in the study is reviewed. It is also considered that how the process parameters affects the morphology. The aim of this communication is to review the relevant literature to understand the morphology of ®lamentous fungi. List of symbols bhyphal density, lm/tip D i impeller diameter, m D pellet diameter (in Eqs. 4 and 5), mm D r dilution rate, h )1 k constant, number of section used for branching (in Eq. 7) K c constant K r constant (in Eq. 5) K r linear colony radial growth rate (in Eq. 1), lm/h L e mean length of main hyphae, lm L e *mean dimensionless length, lm L t mean total length of hyphae, lm L hgu mean length of hyphal growth unit, lm M 0 dry weight of mycelia at time t 0 , g M 1 dry weight of mycelia at time t 1 , g n number of disrupted pellets N impeller speed, h )

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“…During the fermentation process, fungal morphology is an important parameter which influences the physical properties of fermentation broth. The rheological behavior is closely related to the morphology and biomass concentrations (Blanch and Bhavaraju 1976;Charles 1978;Metz et al 1979;Tucker and Thomas 1993). The broth rheology determines the transport phenomena in bioreactors and is considered to be the key factor for getting an improved yield of the targeted product (Berovic et al 1991;Gehrig et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Effect of transport phenomena of Cladosporium cladosporioides on decolorization and chemical oxygen demand of distillery spent wash

Rajarathinam¹

2014

Int. J. Environ. Sci. Technol.

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The focus of this report is directed towards the influence of transport properties of fermentation broth in degradation and decolorization of distillery spent wash using Cladosporium cladosporioides. Batch experiment was conducted in a bioreactor for 7 days with 250 rpm at 35°C under optimum bioprocess conditions maintained using control system. Results of the morphological analysis revealed that C. cladosporioides has been observed to form mainly pellets during fermentation under mild agitation. The organism changed from filamentous form to pellet and then breaks, ending with filamentous form. All the models Power law, Bingham plastic, and Herschel-Bulkley fitted the general trend well with high R 2 values ranging from 0.9 to 0.98, indicating shear rate thinning nature of the broth. A maximum decolorization of 72.3 % was achieved with chemical oxygen demand reduction of 74.8 % due to the low viscous and pellet nature of the organism, leading to the transport properties of the fluid. Hence, transport phenomena channalyze the metabolic path way easily and leads to a novel approach for the industries to utilize the spent wash with minimum cost.

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Non‐Newtonian fermentation broths: Rheology and mass transfer

Cited by 94 publications

References 56 publications

Submerged citric acid fermentation: rheological properties ofAspergillus niger broth in a stirred tank reactor

Submerged citric acid fermentation: rheological properties ofAspergillus niger broth in a stirred tank reactor

Understanding the morphology of fungi

Effect of transport phenomena of Cladosporium cladosporioides on decolorization and chemical oxygen demand of distillery spent wash

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